Fixed: moved the "can't cast to T because it was never instantiated" error...

Fixed: moved the "can't cast to T because it was never instantiated" error from compile-time to runtime

spec/compiler/codegen/cast_spec.cr

@@ -271,4 +271,27 @@ describe "Code gen: cast" do
       (a as Void*).address
       )).to_i.should_not eq(0)
   end
+
+  it "errors if casting to a non-allocated type" do
+    run(%(
+      require "prelude"
+
+      class Foo
+      end
+
+      class Bar < Foo
+      end
+
+      class Baz < Foo
+      end
+
+      foo = Foo.new || Bar.new
+
+      begin
+        foo as Baz
+      rescue ex
+        ex.message.includes?("can't cast to Baz because it was never instantiated")
+      end
+      )).to_b.should be_true
+  end
 end

spec/compiler/type_inference/cast_spec.cr

@@ -129,23 +129,6 @@ describe "Type inference: cast" do
       "can't cast Pointer(Void) to ( -> Int32)"
   end
 
-  it "errors if casting to a non-allocated type" do
-    assert_error %(
-      class Foo
-      end
-
-      class Bar < Foo
-      end
-
-      class Baz < Foo
-      end
-
-      foo = Foo.new || Bar.new
-      foo as Baz
-      ),
-      "can't cast to Baz because it was never instantiated"
-  end
-
   it "doesn't error if casting to a generic type" do
     assert_type(%(
       class Foo(T)

src/compiler/crystal/semantic/after_type_inference_transformer.cr

@@ -334,7 +334,11 @@ module Crystal
         end
       end
 
-      call = Call.global("raise", StringLiteral.new(ex_msg))
+      build_raise ex_msg
+    end
+
+    def build_raise(msg)
+      call = Call.global("raise", StringLiteral.new(msg))
       call.accept TypeVisitor.new(@program)
       call
     end
@@ -481,7 +485,7 @@ module Crystal
         end
       else
         unless to_type.allocated
-          node.to.raise "can't cast to #{to_type} because it was never instantiated"
+          return build_raise "can't cast to #{to_type} because it was never instantiated"
         end
 
         resulting_type = obj_type.filter_by(to_type)